So you get:

Could not find method bootRepackage() for arguments…

$ ./gradlew clean

FAILURE: Build failed with an exception.

* Where:
Build file '...\build.gradle' line: 25

* What went wrong:
A problem occurred evaluating project ':my-project'.
> Could not find method bootRepackage() for arguments [build...] on project ':...' of type org.gradle.api.Project.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

* Get more help at https://help.gradle.org

BUILD FAILED in 2s

Fix

From: spring.io/blog/2017/04/05/spring-boot-s-new-gradle-plugin

The bootRepackage task has been replaced with bootJar and bootWar tasks for building executable jars and wars respectively. Both tasks extend their equivalent standard Gradle jar or war task, giving you access to all of the usual configuration options and behaviour.

So, change your bootRepackage to bootJar (or bootWar, but most probably bootJar).

That’s it.

Note: If you had bootRepackage { enabled = false } you are probably doing it wrong. I suggest you just don’t apply spring boot’s plugin to that project (module) – in other words, remove apply plugin: 'org.springframework.boot'.
You may have some trouble getting the dependencies when you remove such plugin. If that’s the case, add apply plugin: "io.spring.dependency-management" as well. Here’s a sample project doing that.